This invention relates to an improved apparatus for raising logs in uniform incremental amounts into the path of a bandsaw blade having a horizontally extending run. The present mechanism enables safer and more efficient sawmill use by facilitating the log handling task associated with sawmill operation.
Several types of portable sawmills are available for cutting lumber from trimmed logs. U.S. Pat. Nos. 3,213,906 and 3,721,146 each disclose sawmills having a bandsaw horizontally mounted in a carriage assembly designed to cut planks from the top of a log. In each of the described sawmills the bandsaw blade not only has longitudinal mobility so that it can be moved down the length of the log during each cut, but it also has vertical mobility so that the blade height can be adjusted relative to the position of the log. Thus after each plank is cut from the top of the log, the blade is lowered by an amount equal to the thickness of the next plank to be cut.
U.S. Pat. No. 4,275,632 discloses a similar portable sawmill having a bandsaw blade with a horizontally extending run mounted on a carriage which straddles the log to be cut. The portable sawmill disclosed in U.S. Pat. No. 4,275,632 differs, however, from the portable sawmills disclosed in the above-cited patents in that the carriage assembly for the bandsaw blade is itself not height adjustable. Instead the log is mounted on a pair of height adjustable log supports. At the end of each cutting stroke the log itself is raised by an amount approximating the thickness of the next plank to be cut from the top of the log. The log supports have height adjustable shelves. The height of the log is adjusted after each cut by using a jacking mechanism to lift each log end so that the height adjustable shelf on the log support at that end can be mounted at a higher position. The jacking mechanism is itself claimed in U.S. Pat. No. 4,334,669. The disclosed jacking mechanism is awkward to use and leaves much to be desired from the point of user safety.
Accordingly, it is an object of this invention to provide a safe and convenient means for raising a log in incremental amounts to be engaged by a horizontally extending bandsaw blade run to cut planks from the top of the log.
It is a further object of the present invention to provide an improved height adjustable log support for use in a bandsaw-type sawmill. These and other objects will be readily apparent from the following description of the invention.